Containers serve to receive contents, for example to receive drinks or powder foodstuffs or other substances. On their upper side, the containers have an opening or mouth. It is frequently desirable or indeed necessary to close this container mouth with a disc-shaped seal which tightly closes off the contents from external influences, that is to say with a sealing disc.
Already known from DE 91 08 868 U1 is a sealing disc which is for closing a container and can be secured to the opening edge of the container by induction sealing. For this purpose, the sealing disc has a metal foil. A very thin plastics foil is mounted on the underside of the metal foil, that is to say on the side adjacent to the opening edge. It is then possible to mount this foil securely to the upper edge by means of induction sealing. If an eddy current is induced in the metal foil from above, the latter is heated accordingly, as is the plastics foil which is located under it and which is thereby melted. This also applies to the upper edge of the container, for example a plastics beaker. A relatively secure connection between the plastics foil and the upper edge of the beaker is produced. The entire mouth region is then additionally covered with a screw cap which mechanically protects the sealing disc and the mouth region.
In order to reach the contents of a container which is still closed by the sealed-on sealing disc, the user must remove the sealing disc in a suitable form from the mouth. For this purpose, there are various hand grips used in practice to simplify this procedure for the user.
DE 10 2007 014 084 B3 discloses for example an outwardly projecting grip tab. This protrudes beyond the opening edge of the container. The user can grasp this grip tab, pull it upward and then remove the sealing disc in one movement.
This concept is widely used and has indeed proved itself in practice. It is disadvantageous that the grip tab that projects outwards beyond the radius of the mouth of the container must be accommodated, before the actual time at which it is needed and used, as far as possible such that on the one hand it is not itself damaged and so can no longer fulfill its purpose, and on the other it does not disrupt the closing procedure. Another consideration is that frequently a screw cap has to be screwed onto and over the mouth of the container, on the outside, and outwardly projecting sealing tabs then have to be designed such that as far as possible they do not enter the screw thread and either impair the seal or become engaged by the thread themselves. There are ways of tackling this, but some of these require a burdensome adaptation of the screw cap or, as in EP 2 045 194 B1, require a complicated folding back of this tab into the interior of the sealing disc, between other layers.
Another idea, as in EP 1 472 153 B1 or DE 199 20 572 A1, consists in forming the uppermost layer of the sealing disc such that it forms a type of upwardly projecting fold which the user can grasp in order to pull the entire sealing disc off upwards.
This construction, which is also widely used, has the disadvantage that the uppermost layer may either be bonded to the layer underneath not over the full surface or may be secured thereto in order that a loose, upwardly projecting and graspable fold is indeed produced, or that the uppermost layer is from the outset formed by additional material, such that it forms with this additional material an upwardly projecting layer that leads back to the base of the fold again.
In both cases, the problem arises that this fold, which then projects loosely upwards, is sensitive to rotary movements of the screw cap thereon and measures have to be taken to protect the fold from damage, despite the fact that it lies loosely on the layers underneath. Moreover, the formation of folds of this kind using partial regions of the surface of the sealing disc is not unproblematic and is thus burdensome.
A further idea is known from EP 1 160 177 B1 and U.S. Pat. No. 5,915,601 A. Here, the attempt is made to provide, in a similar form, in the central region of the upper side of the sealing disc a hand grip for the user that he or she can pull on in order to lift up the sealing disc as a whole. For this purpose, a perforation is provided which delimits on three sides an approximately rectangular piece of the surface in the central region, on the upper side of the sealing disc. The user can then in part isolate this piece of the surface in the weakest region by separating it along the perforation, grasp it and lift it and, by way of the remaining piece connecting the rectangular surface to the rest of the sealing disc, attempt to use this piece of the surface as a hand grip and pull the entire sealing disc off upwards.
However, this is not unproblematic, since it is very difficult for the user to predict and control the precise behaviour of the sealing disc. Moreover, the points at which the force from pulling up the tab that is formed is introduced into the rest of the sealing disc are highly unfavourable and may result in uncontrolled tearing off at a point which may be undesirable.
If an upwardly projecting fold or outwardly jutting tab is dispensed with and the user is given no hand grip for the purpose of opening, then the user must try to destroy the sealing disc by force using a knife or other object, or in some cases using his or her fingers, in order to reach the contents. This is frequently unappealing to users and results in the container contents being spilled, since in this case these opening procedures are uncoordinated and are also difficult for the manufacturer of the respective product to predict.
This situation is very unsatisfactory. It would therefore be highly desirable if there were a way of providing users with a hand grip without needing to provide folds or similar that can be set upright or are upright for the purpose of being pulled up, or outwardly projecting or fold-up tabs.